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Groups > linux.kernel > #1271307

[PATCH 4/4] iommu/vt-d: Do access checks before calling handle_mm_fault()

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From: Joerg Roedel <jroedel@suse.de>

Not doing so is a bug and might trigger a BUG_ON in
handle_mm_fault(). So add the proper permission checks
before calling into mm code.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/intel-svm.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index c69e3f9..5046483 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -484,6 +484,23 @@ struct page_req_dsc {
 };
 
 #define PRQ_RING_MASK ((0x1000 << PRQ_ORDER) - 0x10)
+
+static bool access_error(struct vm_area_struct *vma, struct page_req_dsc *req)
+{
+	unsigned long requested = 0;
+
+	if (req->exe_req)
+		requested |= VM_EXEC;
+
+	if (req->rd_req)
+		requested |= VM_READ;
+
+	if (req->wr_req)
+		requested |= VM_WRITE;
+
+	return (requested & ~vma->vm_flags) != 0;
+}
+
 static irqreturn_t prq_event_thread(int irq, void *d)
 {
 	struct intel_iommu *iommu = d;
@@ -539,6 +556,9 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 		if (!vma || address < vma->vm_start)
 			goto invalid;
 
+		if (access_error(vma, req))
+			goto invalid;
+
 		ret = handle_mm_fault(svm->mm, vma, address,
 				      req->wr_req ? FAULT_FLAG_WRITE : 0);
 		if (ret & VM_FAULT_ERROR)
-- 
1.9.1

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[PATCH 0/4 v2] Implement access checks in iommu page fault paths Joerg Roedel <joro@8bytes.org> - 2015-11-17 16:20 +0100
  [PATCH 1/4] iommu/amd: Do proper access checking before calling handle_mm_fault() Joerg Roedel <joro@8bytes.org> - 2015-11-17 16:20 +0100
  [PATCH 2/4] iommu/amd: Correctly set flags for handle_mm_fault call Joerg Roedel <joro@8bytes.org> - 2015-11-17 16:20 +0100
  [PATCH 3/4] iommu/amd: Cleanup error handling in do_fault() Joerg Roedel <joro@8bytes.org> - 2015-11-17 16:20 +0100
  [PATCH 4/4] iommu/vt-d: Do access checks before calling handle_mm_fault() Joerg Roedel <joro@8bytes.org> - 2015-11-17 16:20 +0100
    Re: [PATCH 4/4] iommu/vt-d: Do access checks before calling  handle_mm_fault() David Woodhouse <dwmw2@infradead.org> - 2015-11-20 16:40 +0100
  Re: [PATCH 0/4 v2] Implement access checks in iommu page fault paths Oded Gabbay <oded.gabbay@gmail.com> - 2015-11-18 15:10 +0100
  Re: [PATCH 0/4 v2] Implement access checks in iommu page fault paths Jesse Barnes <jbarnes@virtuousgeek.org> - 2015-11-18 17:20 +0100
    Re: [PATCH 0/4 v2] Implement access checks in iommu page fault paths Joerg Roedel <joro@8bytes.org> - 2015-11-27 13:10 +0100

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